Ch 8 provides a detailed study of cell structure — cell theory, differences between prokaryotic and eukaryotic cells, and the structure and function of all major cell organelles.
Cell theory (Schleiden & Schwann): all organisms are made of cells; cell is the basic structural/functional unit; all cells arise from pre-existing cells. Prokaryotic: no membrane-bound nucleus (bacteria), nucleoid region, 70S ribosomes. Eukaryotic: membrane-bound organelles, 80S ribosomes, linear chromosomes.
Endomembrane system: ER (rough — ribosomes, proteins; smooth — lipids) → Golgi (packaging, modification) → lysosomes (digestion) → vacuoles (storage). Mitochondria: double membrane, matrix, cristae, own circular DNA, 70S ribosomes, ATP synthesis (oxidative phosphorylation). Chloroplast: thylakoids (grana + stroma lamellae), stroma, own DNA, photosynthesis. Nucleus: nuclear envelope with pores, chromatin (DNA + histones), nucleolus (rRNA synthesis).
Download: https://ncert.nic.in/textbook/pdf/kebo108.pdf | Complete book: https://ncert.nic.in/textbook/pdf/kebo1ps.zip
Mitochondria have their own circular DNA, 70S ribosomes, and can synthesise some of their own proteins. They can self-replicate by fission. However, most mitochondrial proteins are encoded by nuclear DNA and imported. So they are partially independent (semi-autonomous). This supports the endosymbiont theory — mitochondria evolved from ancient bacteria.
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